U.S. patent application number 12/157420 was filed with the patent office on 2009-12-10 for digital repeater module and method for relaying digital data.
This patent application is currently assigned to DISNEY ENTERPRISES, INC.. Invention is credited to Peter Doherty, Gary J. Nadler, Steve Schwartz.
Application Number | 20090304046 12/157420 |
Document ID | / |
Family ID | 41400278 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090304046 |
Kind Code |
A1 |
Nadler; Gary J. ; et
al. |
December 10, 2009 |
Digital repeater module and method for relaying digital data
Abstract
There is provided a digital repeater module and method for
relaying digital data. The digital repeater module comprises a data
reception unit configured to receive digital data from several
broadcast devices concurrently, a data transmission unit configured
to transmit digital data using a multiple transmission protocols
concurrently, and a routing application. The routing application
can receive digital data through the data reception unit, identify
available data paths for relaying the digital data to desired
destinations, and determine transmission metrics for each of the
available data paths for relaying the digital data to the desired
destinations. The routing application can also select data paths
for transmission based on the determined transmission metrics, and
transmit the digital data using the selected data paths through the
data transmission unit. There is also provided a method for
resolving assignment of limited broadcast frequencies using the
digital repeater module.
Inventors: |
Nadler; Gary J.; (Marlboro,
NJ) ; Doherty; Peter; (Rockville, MD) ;
Schwartz; Steve; (Bellmore, NY) |
Correspondence
Address: |
DISNEY ENTERPRISES;C/O FARJAMI & FARJAMI LLP
26522 LA ALAMEDA AVENUE, SUITE 360
MISSION VIEJO
CA
92691
US
|
Assignee: |
DISNEY ENTERPRISES, INC.
BURBANK
CA
|
Family ID: |
41400278 |
Appl. No.: |
12/157420 |
Filed: |
June 9, 2008 |
Current U.S.
Class: |
375/141 ;
375/211; 375/E1.002 |
Current CPC
Class: |
H04W 28/18 20130101;
H04W 72/0453 20130101; H04L 45/12 20130101; H04B 7/155 20130101;
H04W 88/04 20130101 |
Class at
Publication: |
375/141 ;
375/211; 375/E01.002 |
International
Class: |
H04B 1/707 20060101
H04B001/707; H04B 7/14 20060101 H04B007/14 |
Claims
1. A digital repeater module for relaying digital data, the digital
repeater module comprising: a data reception unit configured to
receive the digital data from a plurality of broadcast devices
concurrently; a data transmission unit configured to transmit the
digital data using a plurality of transmission protocols
concurrently; and a routing application to: receive digital data
through the data reception unit; identify available data paths for
relaying the digital data to desired destinations; determine
transmission metrics for each of the available data paths for
relaying the digital data to the desired destinations; select a
plurality of data paths for transmission based on the determined
transmission metrics; and transmit the digital data using the
selected plurality of data paths through the data transmission
unit.
2. The digital repeater module of claim 1, wherein the digital data
comprises video data.
3. The digital repeater module of claim 1, wherein the digital data
comprises Global Positioning System and frequency data.
4. The digital repeater module of claim 1, wherein the broadcast
devices comprise a plurality of electronic newsgathering (ENG)
vehicles and wireless portable cameras.
5. The digital repeater module of claim 1, wherein the data
reception unit includes a plurality of microwave receivers.
6. The digital repeater module of claim 1, wherein the data
reception unit includes a receiver for an adjustable local
camera.
7. The digital repeater module of claim 1, wherein the data
transmission unit includes wireless communication links.
8. The digital repeater module of claim 1, wherein the data
transmission unit includes wired communication links.
9. A method for use by a digital repeater module for relaying
digital data, the method comprising: receiving digital data through
a data reception unit configured to receive from a plurality of
broadcast devices concurrently; identifying, using a routing
application, available data paths for relaying the digital data to
desired destinations; determining, using the routing application,
transmission metrics for each of the available data paths for
relaying the digital data to the desired destinations; selecting,
using the routing application, a plurality of data paths for
transmission based on the determined transmission metrics; and
transmitting the digital data using the selected plurality of data
paths through a data transmission unit configured to transmit using
a plurality of transmission protocols concurrently.
10. The method of claim 9, wherein the digital data comprises video
data.
11. The method of claim 9, wherein the digital data comprises
Global Positioning System and frequency data.
12. The method of claim 9, wherein the broadcast devices comprise a
plurality of electronic newsgathering (ENG) vehicles and wireless
portable cameras.
13. The method of claim 9, wherein the data reception unit includes
a plurality of microwave receivers.
14. The method of claim 9, wherein the data reception unit includes
a receiver for an adjustable local camera.
15. The method of claim 9, wherein the data transmission unit
includes wireless communication links.
16. The method of claim 9, wherein the data transmission unit
includes wired communication links.
17. A method for use by a digital repeater module for resolving
assignment of limited broadcast frequencies, the method comprising:
receiving frequency and Global Positioning System data from a first
broadcasting device; transmitting the frequency and the Global
Positioning System data to a frequency coordinator site assigned to
the first broadcasting device; receiving from the frequency
coordinator site instructions to relay to a second broadcasting
device; and sending the instructions to the second broadcasting
device to resolve possible frequency conflicts between the first
broadcasting device and the second broadcasting device.
18. The method of claim 17, wherein the first broadcast device is
an electronic newsgathering (ENG) vehicle or a wireless portable
camera.
19. The method of claim 17, wherein the second broadcast device is
an electronic newsgathering (ENG) vehicle or a wireless portable
camera.
20. The method of claim 17, wherein the instructions comprise
changing frequency.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to electronic
circuits and systems. More particularly, the present invention
relates to communications systems for transmission of digital
data.
[0003] 2. Background Art
[0004] Television news provides the public with coverage of
interesting and relevant local news and events, assists law
enforcement in finding and identifying crime suspects, and informs
the public with early warning and ongoing coverage concerning
emergencies and disasters such as fires, earthquakes, storms,
terrorism, and other threats. Reliable transmission of these news
stories can be vital for ensuring public safety. Besides news,
television stations often provide entertainment, such as real time
feeds of ongoing special events. Sporting games, parades, and live
performances happening across the street or around the world are
conveniently viewable at home thanks to these broadcasts. However,
before these broadcasts reach their final destination at the
viewer's television, they must first be recorded from cameras,
often far away from the television studio. Thus, different
techniques and devices have been developed to accomplish the task
of transferring the camera footage to a desired location, usually a
television station studio, to be disseminated to the wider
public.
[0005] Electronic News Gathering (ENG) is an acronym that generally
describes the process of a newscaster or television crew going out
and covering a news story. One method used for video footage
transfer in ENG is transmission through short-range direct line of
sight microwaves. Generally, a vehicle such as a truck or van is
specially modified with video equipment and a microwave
transmission dish. The microwave transmission dish is often mounted
on a telescoping mast that can rise about fifty feet into the air
to achieve direct line of sight with a receive tower. The vehicle
itself may also receive short-hop signals from, for example,
portable cameras. Video production and editing equipment in the
vehicle might be used to prepare video footage for broadcast. From
that point, the edited video or raw footage may be sent via
microwave transmission to a relay tower or directly to a central
receive tower at the home studio. The relay towers might be
strategically placed throughout the desired coverage area to allow
greater reporting distance from the home studio.
[0006] Although microwaves work well when there is a clear and
unobstructed path, if there is sufficient interference from, for
example, adverse weather conditions, line of sight barriers, and
interfering microwaves on nearby frequencies, microwave signal
quality may degrade to the point of uselessness. In particular, the
availability of microwave spectrum frequencies is extremely
limited, requiring news agencies to carefully coordinate their
microwaves not to interfere with each other. Regulations also limit
the amount of microwave energy allowed for broadcast, further
limiting microwave signal integrity. Thus, microwave transmission
is not a completely reliable method of transfer, especially when
operating far away from the central receive tower.
[0007] Another common method of transfer used by ENG is satellite
communications. The specially modified vehicle previously mentioned
might also be equipped with a satellite dish to supplant or
complement the existing microwave transmission capabilities. The
satellite dish is pointed skywards to a geostationary satellite,
data is sent to the satellite, and the satellite relays that data
back to the home studio. Thus, distance from the central receive
tower is no longer a concern, as long as there is a clear path to
the satellite. However, satellites suffer from similar transmission
availability problems as microwave, such as limited satellite
lifetime, limited frequency availability, interference, malfunction
downtimes, and signal loss susceptibility in adverse weather
conditions. Thus, satellite communications still inherit many
unaddressed reliability concerns.
[0008] Accordingly, there is a need to overcome the drawbacks and
deficiencies in the art by providing a way for video footage and
other digital data to be reliably transferred from a remote
location to desired destinations.
SUMMARY OF THE INVENTION
[0009] A digital repeater module and method for relaying digital
data, substantially as shown in and/or described in connection with
at least one of the figures, as set forth more completely in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The features and advantages of the present invention will
become more readily apparent to those ordinarily skilled in the art
after reviewing the following detailed description and accompanying
drawings, wherein:
[0011] FIG. 1 presents a diagram of a digital repeater module, in
accordance with one embodiment of the present invention;
[0012] FIG. 2 presents a digital repeater system including multiple
digital repeater modules for relaying digital data, in accordance
with one embodiment of the present invention;
[0013] FIGS. 3A and 3B present a block diagram at two points in
time showing in greater detail an exemplary digital repeater module
by which limited broadcast frequencies may be assigned to broadcast
devices by the digital repeater module;
[0014] FIG. 4 shows a flowchart describing the steps, according to
one embodiment of the present invention, by which a digital
repeater module may relay digital data; and
[0015] FIG. 5 shows a flowchart describing the steps, according to
one embodiment of the present invention, by which a digital
repeater module may resolve assignment of limited broadcast
frequencies.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The present application is directed to a digital repeater
module and method for relaying digital data. The following
description contains specific information pertaining to the
implementation of the present invention. One skilled in the art
will recognize that the present invention may be implemented in a
manner different from that specifically discussed in the present
application. Moreover, some of the specific details of the
invention are not discussed in order not to obscure the invention.
The specific details not described in the present application are
within the knowledge of a person of ordinary skill in the art. The
drawings in the present application and their accompanying detailed
description are directed to merely exemplary embodiments of the
invention. To maintain brevity, other embodiments of the invention,
which use the principles of the present invention, are not
specifically described in the present application and are not
specifically illustrated by the present drawings.
[0017] FIG. 1 presents a diagram of a digital repeater module shown
in the context of a digital repeater environment, in accordance
with one embodiment of the present invention. Digital repeater
environment 100 includes digital repeater module 110, local camera
156, antenna multi-coupler 136, antennas 140, 153, 154, and 155,
and broadcast devices 150, 151, and 152. Digital repeater module
110 includes data reception unit 120, data transmission unit 130,
and routing application 160. Routing application 160 controls the
flow of data between data reception unit 120 and data transmission
unit 130. Connected to data reception unit 120 are antennas 153,
154, and 155, which receive broadcasts from broadcast device 150,
151, and 152, respectively. Local camera 156 is also connected to
data reception unit 120. Connected to data transmission unit 130
are various communication protocol links, including microwave link
131, satellite link 132, Evolution Data Only/Evolution Data
Optimized (EVDO) link 133, Worldwide Interoperability for Microwave
Access (WiMax) link 134, WiFi link 135, Ethernet link 137, fiber
optic link 138, and Asynchronous Serial Interface (ASI) cable link
139. Antenna multi-coupler 136 is connected to EVDO link 133, WiMax
link 134, and WiFi link 135 and allows these protocols to share the
same antenna 140.
[0018] For the sake of clarity, FIG. 1 is lacking certain
implementation details such as particular hardware embodiments,
microprocessors, storage devices, power supplies, and other
details. The selection and configuration of appropriate supporting
hardware is well known in the art. One particular point that may
merit some discussion is the redundancy of the power supply. Since
high availability of digital repeater module 110 is important for
reliable data communications, a digital repeater module power
supply (not shown in FIG. 1) might be supported by backup power
systems, including, for example, a battery backup or a solar panel
generator (also not shown in FIG. 1). This may be especially
important in situations involving national security or public
safety.
[0019] For the present example, consider a hypothetical television
station named KXYZ, which owns or has the rights to use the
equipment and communication links shown in FIG. 1. Broadcast
devices 150, 151, and 152, might then, for example, represent
microwave equipped ENG vehicles with video editing and camera
equipment. However, in another embodiment, the broadcast devices
might also include independent wireless portable cameras, which can
connect to an uplink wirelessly without relying on an ENG vehicle
as an uplink relay. In other embodiment, any device that can
leverage an enhanced ability to transport data reliably might also
be utilized a broadcast device candidate, although for the sake of
simplicity, FIG. 1 illustrates microwave equipped ENG vehicles as
an example of broadcast devices. For example, a wireless laptop
could be used as a broadcast device, leveraging an enhanced ability
to exchange files with the home studio to improve collaboration and
productivity.
[0020] Continuing with the present example, there might be three
breaking stories in the area close to digital repeater module 110,
so broadcast devices 150, 151, and 152 are concurrently covering
each of the stories. Each of the broadcast devices then orients
their microwave dish towards data reception unit 120 of digital
repeater module 110. Although the present example utilizes
directional microwaves, modem microwave transmission techniques
such as coded orthogonal frequency-division multiplexing (COFDM)
might circumvent the need for a direct line of sight, dispensing
with the directional orientation step necessary for a directional
microwave dish. This alternative technique can often be used in
highly mobile broadcast environments such as motorcycles and
helicopters, where it may be impractical to constantly realign the
broadcast antenna due to positional movement.
[0021] In FIG. 1, the example directional microwaves from the
broadcast devices are connected to three separate reception
antennas, e.g. antennas 153, 154, and 155. Three antennas are
chosen simply to emphasize the multiple input capability of data
reception unit 120; there can be more or less antennas, or it could
comprise a smart antenna array or some other advanced configuration
capable of receiving multiple inputs. In addition, although data
reception unit 120 in this example is receiving data primarily from
microwave broadcasting devices used in ENG applications, data
reception unit 120 may potentially receive inputs from several
different transmission protocols, depending on the desired
application.
[0022] One alternative input that data reception unit 120 might
receive from is local camera 156, which may be connected to data
reception unit 120 through a direct cable connection or a short-hop
wireless link, for example. Since high bandwidth microwave
transmission requires a direct line of sight, digital repeater
module 110 might be placed in a position for high antenna
visibility such as the rooftop of a building. Although modem
microwave techniques such as COFDM may avoid the need for direct
line of sight, compatibility with existing equipment might still
favor placement at high vantage points. Often, this placement is
also advantageous for taking panoramic views of surrounding events,
which is where local camera 156 may prove to be useful. Local
camera 156 might have various positioning and angle adjustments
built into it, allowing for flexible focus on areas of interest. To
control these adjustments, data reception unit 120 might issue
commands to local camera 156 to adjust its height, angle, zoom, and
focus. Those commands might originate from a remote location, such
as from an Internet web interface hosted at the KXYZ studio, or
from one of the broadcast devices 150, 151, and 152.
[0023] Although the connections to data reception unit 120 are
portrayed as one-way in FIG. 1, this is only to emphasize the
predominant direction of data transfer and does not preclude
bidirectional communication such as the camera adjustment commands
discussed above. Depending on the requirements of the ENG teams and
the unavailability of other communication links, data reception
unit 120 might even send significant amounts of data back to
broadcast devices 150, 151, and 152. Thus, data reception unit 120
and data transmission unit 130 might both be individually referred
to as all-in-one data reception and transmission units. However,
they are separated as a reception unit and a transmission unit to
emphasize the predominant direction of data transfer, which is
often vital for configuring the implementing hardware. For example,
antennas configured for optimal reception are often poorly
configured for optimal transmission, and vice versa. Thus, if the
ENG teams require large amounts of data to be sent back to
broadcast devices 150, 151, and 152, data transmission unit 130
should be preferred to data reception unit 120, if appropriate
communications links are available.
[0024] Data transmission unit 130 is configured to be as flexible
as possible in the number of different transmission protocols it
can understand and use. As previously mentioned, data transmission
unit 130 may be capable of bidirectional communication but is
optimized for transmitting data. In the present example, there are
eight (8) possible communication links data transmission unit 130
can utilize, but another embodiment may support a different
configuration of multiple communication links. In FIG. 1, the
communication links are separated into three different groups. The
top group consists of microwave link 131 and satellite link 132,
which represent the traditional methods of communication for ENG
vehicles and cameras. These links may use a dish antenna to
transmit signals. The middle group consists of EVDO link 133, WiMax
link 134, and WiFi link 135, representing various wireless radio
protocols. In this particular embodiment, they are configured to
share the same antenna 140 through the use of antenna multi-coupler
136. Antenna 140 might consist of a smart antenna array that can
reconfigure itself for the most appropriate method of transmission.
The bottom group consists of Ethernet link 137, fiber optic link
138, and ASI cable link 139, which represent wired connector
communications. These wired connectors may further connect to a
local area network (LAN), which in turn may connect to a wide area
network such as the Internet.
[0025] Routing application 160 contains the logic to route data
from data reception unit 120 through data transmission unit 130
based on some determined transmission metrics. These metrics might
comprise, for example, speed of transfer, latency, link
reliability, power consumption, and cost performance. One
particular metric might be isolated if it is of prime importance,
for example, maximization of link reliability. Alternatively, a
combination of weighted metrics might be used to assign relative
importance to certain metrics. Metrics might also be selected based
on the content of transmission; for example, emergency broadcasts
might prioritize speed of transfer and link reliability, whereas
entertainment broadcasts might emphasize latency and cost
performance. These selected metrics are the relevant measure of
interest when data paths of "optimal" or "sub-optimal" performance
are referred to in this specification. More details about the
operation of routing application 160 shall be deferred for the
discussion of FIG. 4 below.
[0026] Now that a single digital repeater module has been
introduced, FIG. 2 presents a digital repeater system including
multiple digital repeater modules for relaying digital data, in
accordance with one embodiment of the present invention. Digital
repeater system 200 includes broadcast device 250, digital repeater
modules 210a, 210b, and 210c, local camera 256, receive site 280d,
and corporate LAN 290. Broadcast device 250 corresponds to
broadcast devices 150, 151, and 152 from FIG. 1, and it can
communicate with digital repeater module 210a by microwave link
231a. Local camera 256 corresponds to local camera 156 in FIG. 1,
and can communicate with digital repeater module 210a by cable link
239a. Digital repeater modules 210a, 210b, and 210c correspond to
digital repeater module 110 in FIG. 1. Digital repeater module 210a
can communicate with digital repeater module 210b by microwave link
231b and satellite link 232b, but transmission barrier 229 is
causing signal integrity problems as indicated by the dotted lines.
Digital repeater module 210a can also communicate with digital
repeater module 210c by microwave link 231c and WiMax link 234c.
Digital repeater module 210b can communicate with receive site 280d
and corporate LAN 290 by fiber link 238d, which is available but
unused as indicated by the dashed line. Digital repeater module
210c can communicate with receive site 280d by WiFi link 235d,
satellite link 232d, and WiMax link 234d, although satellite link
232d is shown to have some transmission problems indicated by the
dotted line. Digital repeater module 210c can also communicate with
corporate LAN 290 by WiMax link 234d.
[0027] Continuing with the KXYZ station example, broadcast device
250 from FIG. 2 may represent a microwave equipped ENG vehicle.
Only one broadcast device is presented in FIG. 2 to simplify the
explanation of digital repeater system 250; there might be many
concurrent broadcast devices as in FIG. 1. Receive site 280d might
represent the KXYZ television studio, where video footage must
arrive before being broadcast to the public. Corporate LAN 290
might represent the business network of KXYZ executives located in
a nearby business suite, but separate from the television studio.
These KXYZ executives might want the ability to monitor the video
footage generated from broadcast device 250. Thus, FIG. 2
illustrates the situation where data from broadcast device 250 is
to be sent concurrently to receive site 280d and corporate LAN 290.
Since the footage will be broadcast the same day it is taken, the
KXYZ engineers decide to emphasize transfer speed and link
reliability as the transmission metrics for selecting optimal data
paths. Digital repeater modules 210a, 210b, and 210c will
coordinate how that is accomplished.
[0028] Starting from the origin of the digital data, a news story
may have been recorded and produced at the ENG vehicle that
represents broadcast device 250. Continuing the KXYZ example, KXYZ
news crew including popular KXYZ news personality Bernard Blintz
are covering a political protest in progress near broadcast device
250. A wireless portable camera records and digitizes ten minutes
of raw video and audio footage and relays the footage back to the
ENG vehicle for post-processing. Furthermore, the wireless portable
camera or the equipment at the ENG vehicle might compress the video
and audio streams into, for example, MPEG-2 or MPEG-4 formats to
accommodate bandwidth and data storage constraints while
maintaining the human perceived quality of the video. Encryption
might also be applied to the data to prevent unauthorized third
parties from intercepting or modifying the data.
[0029] At the ENG vehicle corresponding to broadcast device 250 in
FIG. 2, the video editing crew splice the ten minutes of raw
footage into a three-minute segment suitable for the allotted time
in the KXYZ evening news program, applying KXYZ logos, text
overlays, transition effects, and otherwise preparing the segment
for prime time. This post-processing step might be deferred for the
crew at the home studio instead, or the raw video data might be
transmitted in real-time for "live" news coverage, but broadcast
device 250 in the present example will be setup to transmit a
prepared and prerecorded file. Thus, a digital data file named
"BERNARD.MPEG" might represent the three-minute Bernard Blintz
segment covering the political protest. As mentioned, as both the
corporate executives and the television studio may be interested in
this file, according to the present example, BERNARD.MPEG can be
sent to both receive site 280d, the television station, and
corporate LAN 290, where the executives are located.
[0030] At the same time Bernard Blintz is on the ground covering
the political protest, local camera 256 might be capturing an
aerial view of the sprawling protest crowd. As previously
discussed, digital repeater module 210a might be ideally located on
a rooftop to maximize antenna visibility, which in turn makes it an
ideal vantage point for local camera 256. Local camera 256 might be
adjustable through remote commands issued by, for example,
broadcast device 250. Since broadcast device 250 is not optimized
for receiving data, it might receive a low bandwidth video feed of
local camera 256 through microwave link 231a to act as a remote
viewfinder. This video feed can help broadcast device 250 to send
proper camera adjustment commands to local camera 256 for focusing
on areas of interest; in this case, the protest crowd. Similar to
the wireless camera, local camera 256 might provide digital
repeater module 210a with a compressed video file named
"CROWD.MPEG" which may be distributed in a similar manner as
BERNARD.MPEG.
[0031] Since the news story may be happening far away from receive
site 280d, broadcast device 250 may be out of range for direct
microwave transmission. In the present example, broadcast device
250 can only communicate by a limited range microwave link, so this
may pose a problem. However, the presence of digital repeater
module 210a within microwave link range, in the present embodiment,
provides a solution to that problem not met by the conventional
art. Although three digital repeater modules are shown as available
in FIG. 2, for the purposes of the present example let us assume
that only digital repeater module 210a is close enough to receive a
signal from broadcast device 250. Thus, broadcast device 250 is
oriented towards digital repeater module 210a and transmits
BERNARD.MPEG. After receiving BERNARD.MPEG, digital repeater module
210a might temporarily cache BERNARD.MPEG on a local storage device
such as flash memory. After digital repeater module 210a is
finished relaying BERNARD.MPEG, this cache might be flushed to free
space on the storage device.
[0032] The desired destinations, i.e., receive site 280d and
corporate LAN 290, might be predetermined at the time of initial
transfer, or the destinations themselves might initiate a request
for the offered file after receiving an offer notification that
BERNARD.MPEG is being distributed by broadcast device 250. This
notify-request system might be implemented using a software
monitoring client that is installed at potential destinations such
as receive site 280d and corporate LAN 290. Even broadcast device
250 might be equipped with the software; for example, it may want
to receive the CROWD.MPEG file generated by local camera 256.
However, the practicality of adding such a feature might be limited
by the data reception capabilities of broadcast device 250. In the
present example, broadcast device 250 is configured primarily for
transmission, so using the data reception software there might be
ill advised.
[0033] From digital repeater module 210a, the files BERNARD.MPEG
and CROWD.MPEG can be relayed to either digital repeater module
210b or digital repeater module 210c. Digital repeater module 210a
might first decide to evaluate the paths to digital repeater module
210b shown by microwave link 231b and satellite link 232b. However,
when determining the transmission metrics of these links, the
routing application of digital repeater module 210a discovers that
the signal integrity and transfer speeds for microwave link 231b
and satellite link 232b are very poor due to transmission barrier
229, which might represent localized adverse weather conditions
between the link paths. Although these particular links are
performing poorly at the time, the overall data paths are not
completely useless as fiber link 238d is available to digital
repeater module 210b as indicated by the dashed lines, supporting
fast and reliable transfers. Transmission barrier 229 will
disappear when the weather clears up, so these particular data
paths might be noted by the routing application for future use.
[0034] The routing application of digital repeater module 210a may
then decide to explore the other available connections: microwave
link 231c and WiMax link 234c. These connections do not encounter
any signal interference problems and digital repeater module 210c
reports excellent signal quality to digital repeater module 210a.
At this point, however, digital repeater module 210a defers the
decision on which paths to select, since there are still some
unknown remaining data paths.
[0035] If the digital repeater modules were configured to consider
only the nearest neighbors, then the decision to transfer to
digital repeater module 210c could be made already. However, the
digital repeater modules may need to consider the overall network
topology rather than just the nearest neighbors when planning data
paths, since problems such as cycles (endless loops) or suboptimal
routes may otherwise result. As an example of a suboptimal route,
an algorithm routing to the nearest optimal neighbor might result
in data transmitting to digital repeater module 210c due to the
presence of transmission barrier 229 before digital repeater module
210b. However, if all outgoing data pathways from digital repeater
module 210c were somehow rendered unavailable, the route that
appeared optimal at first would be a dead end and possibly require
backtracking. An optimal route might go to digital repeater module
210b instead, even with transmission barrier 229, since a weak
signal is better than no signal.
[0036] To avoid suboptimal routes, the digital repeater modules
might learn network topology data from each other on an ad-hoc
peer-to-peer basis, for example, or the network topology data might
be managed in a more centralized fashion. This way, the digital
repeater modules can plan optimal data paths multiple steps ahead.
In one embodiment, digital repeater module 210a is configured to
plan an optimal data path all the way to the final destination.
Methods for creating and maintaining this network topology data are
well known in the art.
[0037] Thus, the routing application must still determine three
paths of unknown signal integrity: WiFi link 235d, satellite link
232d, and WiMax link 234d. WiFi link 235d and WiMax link 234d
indicate no problems, but satellite link 232d seems to be down as
indicated by the dotted line. This situation might represent, for
example, a satellite that is taken out of orbit, having been struck
by a big piece of space debris. Digital repeater module 210a might
inquire digital repeater module 210c as to the available data
paths, and digital repeater module 210c might respond with WiFi
link 235d and WiMax link 234d, along with their transmission
metrics. This peer-to-peer information exchange might facilitate
the process of building the network topology data as previously
discussed. At this point, no other avenues of communication are
known to be available, so digital repeater module 210a parses the
data paths it has available using the routing application and
selects data paths emphasizing transfer speed and link
reliability.
[0038] Thus, digital repeater module 210a will decide to transfer
BERNARD.MPEG and CROWD.MPEG to digital repeater module 210c.
However, as indicated by FIG. 2, there are two paths available;
microwave link 231c and WiMax link 234c. Digital repeater module
210a will need to make a decision on how to use these available
links using the routing application. In a typical configuration,
only one data link would be selected, and the other available links
would remain idle. However, digital repeater module 210a can be
configured to utilize all paths available to it concurrently.
[0039] For the purposes of the present example, a mirrored data
path method, in which mirrored copies of the same data are sent
across all data paths, will be used to increase data transfer
reliability while simplifying the burdens on the routing
application. Thus, a duplicate copy of both BERNARD.MPEG and
CROWD.MPEG will be sent across both microwave link 231c and WiMax
link 234c. Other methods could be adopted or even adaptively
selected based on the current metric emphasis. For example, if
power consumption is selected as a high priority metric, certain
watt expensive paths may not be used concurrently unless justified
by a greater performance or reliability gain. On the other hand, if
transfer speed is the highest priority with link reliability being
a lesser concern, another method for concurrent data transmission
may be selected. As the emphasis on the metrics change, the routing
application may correspondingly adjust its concurrent link
strategies.
[0040] Returning to the present example, digital repeater module
210c now has a copy of BERNARD.MPEG and CROWD.MPEG cached in its
local storage device. Depending on the aggressiveness of the
caching algorithm and the capacity of the storage device, digital
repeater module 210a might take the opportunity to flush
BERNARD.MPEG and CROWD.MPEG from its local cache. However, it may
be deemed beneficial to keep cached copies at different digital
repeater modules for as long as possible, at least until the data
has finally reached its destination. This way, should certain data
links go down and alternative data links need to be pursued,
suboptimal retransmission of data may be avoided as the file would
already exist in some of the digital repeater modules closer to an
optimal path.
[0041] As previously mentioned, satellite link 232d was determined
to be unavailable, so only WiFi link 235d and WiMax link 234d are
available for digital repeater module 210c to use. However, WiMax
link 234d is depicted having two branching arrows going to both
receive site 280d and corporate LAN 290. Fiber link 238d is also
depicted in FIG. 2 as having a similar capability. This illustrates
another transmission capability of the digital repeater modules:
sending concurrently to multiple targets, or multicasting. Digital
repeater module 210c can concurrently send copies of BERNARD.MPEG
and CROWD.MPEG to both receive site 280d and corporate LAN 290.
Conventional unicast transfer, on the other hand, must send two
identical copies sequentially, placing a greater bandwidth burden
on the communications link and requiring a longer transfer time.
Combining this multicast capability with the ability to use
multiple communications links, digital repeater module 210c could
send BERNARD.MPEG and CROWD.MPEG to receive site 280d using
mirrored data across both WiFi link 235d and WiMax link 234d, while
concurrently sending those same data files to corporate LAN 280d
over singular WiMax link 234d. After this step is complete, receive
site 280d and corporate LAN 290 will both have access to local
copies of BERNARD.MPEG and CROWD.MPEG. At this point, a message
might be propagated throughout the digital repeater modules
informing them that the data reached its destination successfully
and that it is safe to flush BERNARD.MPEG and CROWD.MPEG from their
local caches.
[0042] With the data arriving safely at its destinations, the KXYZ
executives using corporate LAN 290 can easily view the BERNARD.MPEG
segment as well as the CROWD.MPEG. Pleased with the footage, the
executives give the studio crew permission to air the segment. At
receive site 280d, the studio crew might splice in segments of
CROWD.MPEG into BERNARD.MPEG to add dramatic impact, and otherwise
polish the segment so that it is ready for prime time broadcast.
Thanks to digital repeater system 200 of FIG. 2, the KXYZ news team
was able to cover a news story that might have been otherwise
outside their usual operating range.
[0043] Moving to FIGS. 3A and 3B, FIGS. 3A and 3B present a block
diagram at two points in time showing in greater detail an
exemplary digital repeater module by which limited broadcast
frequencies may be assigned to broadcast devices by the digital
repeater module. In a crowded and competitive news environment with
limited useable spectrum bands, each television station will have
only a small subset of frequencies to use. If equipment is not
coordinated properly, nearby equipment on similar frequencies may
cause unwanted interference. To that end, digital repeater module
310 shown in FIGS. 3A and 3B operates to facilitate the assignment
of these limited broadcast frequencies.
[0044] Examining FIGS. 3A and 3B in greater detail, FIG. 3A
represents a point in time where frequency interference may be
imminent; FIG. 3B represents a point in time after frequencies are
reassigned. Digital repeater environment 300 includes GPS (Global
Positioning System) satellite 370, broadcast devices 350 and 351,
digital repeater module 310, and frequency coordinator site 345.
Broadcast devices 350 and 351 correspond to broadcast devices 150,
151, and 152 from FIG. 1. Digital repeater module 310 corresponds
to digital repeater module 110 from FIG. 1. GPS satellite 370 can
communicate with broadcast devices 350 and 351 through satellite
links 332a and 332b, respectively. Digital repeater module 310 can
communicate with broadcast device 350, broadcast device 351, and
frequency coordinator site 345 through links 371, 372, and 373
respectively. Distance 325, not drawn to scale, represents the
distance between broadcast devices 350 and 351.
[0045] The systems shown in FIGS. 3A and 3B are simplified for
illustrative purposes. For example, although only one GPS satellite
is depicted, in practice, GPS location data is usually calculated
through data from multiple GPS satellites to improve positioning
accuracy. Similarly, only two broadcast devices and one receive
site are depicted, even though digital repeater module 310 could be
transferring through many more inputs and outputs, and multiple
digital repeater modules might coexist as illustrated in FIG. 2.
Additionally, since the particular method of communication is not
crucial for the present illustration, links 371, 372, and 373 are
presented as bidirectional generic links that might be considered
always available.
[0046] Continuing with the KXYZ example, broadcast devices 350 and
351 could represent microwave equipped ENG vehicles owned by KXYZ,
and frequency coordinator site 345 could represent a room within
the KXYZ studio, located at receive site 280d in FIG. 2. Frequency
coordinator site 345 might include a team of KXYZ engineers,
spectrum analysis equipment, and other tools for maintaining
frequency assignment of KXYZ broadcast devices, for example. GPS
satellite 370 provides location tracking data to broadcast devices
350 and 351 through satellite links 332a and 332b. GPS receive
capability might be added to broadcast devices 350 and 351 by an
add-on GPS receiver or by an interface module utilizing a
preinstalled GPS receiver in the ENG vehicle. If broadcast devices
350 and 351 are wireless cameras instead, a GPS attachment module
might connect to the wireless cameras via a user data channel.
[0047] Broadcast devices 350 and 351 are shown in FIG. 3A to
broadcast on the same frequency A. This could potentially cause
interference problems if distance 325 becomes too short. In order
to detect this, frequency coordinator site 345 will need updated
information about the position and frequency of the broadcast
devices. Broadcast devices 350 and 351 might retrieve their current
position from GPS satellite 370 and periodically forward that GPS
information along with frequency data to digital repeater module
310. Digital repeater module 310 could then relay that GPS
information and frequency data to frequency coordinator site 345.
Using the GPS information and frequency data gathered from
broadcast devices 350 and 351 and other broadcast devices KXYZ
might own, frequency coordinator site 345 could implement an
advanced warning system.
[0048] For example, one advanced warning system could simply set a
maximum threshold distance and trigger a warning should the
distance between two potentially interfering broadcast devices drop
below that threshold. Another method might divide the area to be
monitored into discrete areas, triggering a warning if two
broadcast devices with the same frequency are in the same discrete
area. A more sophisticated system based on predictive movement
patterns might be used to minimize false warnings and defer
frequency changes until absolutely necessary. Alternatively, the
system may focus on providing information rather than making
decisions, relying on human judgment to decide when a warning is
proper. For the KXYZ example, the simple maximum threshold method
will be used.
[0049] When frequency coordinator site 345 does decide to issue a
warning, it must then decide a course of action to take--for
example, changing the frequency of a broadcasting device, turning
off a broadcasting device, or just ignoring the warning in
anticipation that that the devices will move apart, rendering the
warning moot. This step might be assisted by human judgment; for
example, the locations and frequencies of the broadcast devices
could be displayed on a visual map for a human frequency controller
to monitor. The human frequency controller could approve or
override a course of action suggested by an automated system, or
manually direct the actions to take. Due to the scarce number of
frequencies available, there may be situations where one broadcast
device must be turned off. Since the decision to favor one
broadcasting device over another is not easily determined
automatically, human judgment may be especially important at this
step. Coverage of one story might be more important than another,
one ENG vehicle might be better equipped than another, or a
particular news team might be preferred to operate in a certain
area versus another team. These sensitive decisions might require
the human insight of KXYZ personnel. For the present example, this
human aided system will be used to make the final judgment.
[0050] Continuing with the KXYZ example, frequency coordinator site
345 might have recently received a periodic GPS and frequency data
update from broadcast device 350. Based on information already
previously received from broadcast device 351, distance 325 is
calculated to be under the maximum threshold allowed before a
warning is issued, and such a warning is issued. The human
frequency controller is presented with the warning, and decides to
change the frequency of broadcast device 351. Using spectrum
analysis equipment and determining open frequencies, the human
frequency controller is able to select an available frequency,
frequency B, to reassign to broadcast device 351.
[0051] To update broadcast device 351, the instruction to change to
frequency B must travel from frequency coordinator site 345 to
broadcast device 351. In FIG. 3A, this can be accomplished by
sending the instruction via link 373 to digital repeater module
310, which in turn relays the instruction to broadcast device 351
using link 372. After broadcast device 351 receives the instruction
to change frequencies, it might automatically proceed to change its
frequency configuration, or wait for permission to change from the
ENG crew. Once this change is accepted, it might also be propagated
via a Data Return Link (DRL) to any local short-hop wireless
cameras that rely on broadcast device 351 for the uplink to the
television station. Alternatively, broadcast device 351 might
represent a wireless portable camera directly, rather than an ENG
vehicle. After the frequency change is effected, FIG. 3B will
illustrate the updated status of digital repeater system 300, with
broadcast device 351 now using frequency B, free of conflicts with
broadcast device 350.
[0052] With this GPS-based frequency reassignment system in place,
KXYZ can now preemptively deal with potential inference problems
rather than reacting to them when they actually happen. Since GPS
satellites are specialized and do not provide a general data
network, the digital repeater module plays a central role in
relaying data from multiple GPS receivers into a single location
for analysis. Although maintaining this system might increase
maintenance costs for KXYZ, the productivity savings in avoiding
interference problems will likely outweigh these maintenance
costs.
[0053] Now that the digital repeater module has been introduced in
various system configurations, FIG. 4 presents a flowchart
describing in greater detail the steps, according to one embodiment
of the present invention, by which a digital repeater module may
relay digital data. Certain details and features have been left out
of flowchart 400 that are apparent to a person of ordinary skill in
the art. For example, a step may comprise one or more substeps or
may involve specialized equipment or materials, as known in the
art. While steps 402 through 410 indicated in flowchart 400 are
sufficient to describe one embodiment of the present invention,
other embodiments of the invention may utilize steps different from
those shown in flowchart 400.
[0054] Referring to step 402 of flowchart 400 in FIG. 4 and digital
repeater environment 100 of FIG. 1, step 402 of flowchart 400
comprises digital repeater module 110 receiving digital data
through data reception unit 120. As illustrated by FIG. 1, data
reception unit 120 can concurrently receive data from numerous
different devices using different protocols. For the purposes of
the present example, only one data source will be considered. In
the present example, broadcast device 150 represents a microwave
transmitting ENG vehicle broadcasting digital video data, antenna
153 represents a microwave reception antenna, and data reception
unit 120 represents coordinating hardware that enables concurrent
data input. Broadcast device 150, corresponding to broadcast device
250 in FIG. 2, sends data to antenna 153, which receives the signal
and provides it to data reception unit 120.
[0055] Continuing with step 404 in FIG. 4 and digital repeater
environment 100 of FIG. 1, step 404 of flowchart 400 comprises
identifying, using routing application 160, available data paths
for relaying the data received in step 402 to desired receive
locations. Referring to digital repeater system 200 of FIG. 2,
digital repeater modules 210a, 210b, and 210c correspond to digital
repeater module 110 in FIG. 1. Thus, a routing application is also
included in each digital repeater module. As previously discussed,
the desired receive locations might be included at the same time
the data is received, or they could be determined by an
offer-request system. For the present example, receive site 280d
and corporate LAN 290 are included as the desired receive
locations.
[0056] As previously discussed, the routing application of digital
repeater module 210a will need to have some information about the
network topology to plan routes beyond its immediate surroundings.
To determine this network topology, digital repeater module 210a
requests available route information from repeater modules 210b and
210c. To facilitate the next step, a request may also be made for
corresponding transmission characteristics of the routes. Although
the network only consists of three digital repeater modules in FIG.
2, if there are additional digital repeater modules available,
there might be additional information requests spreading out
through the network. When these route requests are answered, they
might also be tagged with a unique route identifier for future use
by the digital repeater modules, circumventing the need to include
the entire path structure when relaying data. This ad-hoc
information gathering system might be augmented or supplanted by a
more centralized system, as previously mentioned. After generating
information about the network topology, digital repeater module
210a can determine the data paths available to route the data, as
represented by the link arrows in FIG. 2.
[0057] At step 406 of flowchart 400, the routing application of
digital repeater module 210a will determine transmission
characteristics for each of the data paths identified in step 404.
If in step 404, transmission characteristics were also requested
along with the available data paths, then this step can be
completed concurrently with step 404. Otherwise, an additional
information request similar to step 404 will need to be executed. A
distinctive aspect of step 406 may be the logic required to provide
the transmission characteristics. For example, transfer speed can
be calculated using a test data transfer, comparing the amount of
data transferred to the time elapsed. Link reliability might be
extrapolated from, for example, the calculated signal to noise
ratio of the receiving antenna, or from uptime history, or from a
number of other parameters. Power consumption might be measured
with a watt measurement device. Latency might be calculated from
timestamp messages, calculating the difference between the sending
of data and the reception of data. If these or any other
characteristics are worth considering, then corresponding logic to
determine those particular characteristics may be embedded into the
routing application. For the present example, transfer speed and
link reliability will be used, link reliability being calculated
from a signal strength calculation.
[0058] At step 408 of flowchart 400, the routing application
selects a plurality of data paths for transmission based on the
transmission characteristics determined from step 406. Referring to
FIG. 2, even if fiber link 238d provides a fast and reliable link,
transmission barrier 229 affects the signal strength to digital
repeater module 210b so severely that the paths going to digital
repeater module 210c will need to be selected instead. As
previously mentioned, the present example will use mirrored data
transfer as the multiple link strategy for simplicity and
reliability. Thus, both microwave link 231c and WiMax link 234c
will be selected in a mirrored data configuration. Since there are
no further branching path choices for digital repeater module 210c
to consider, it will transfer the data using all remaining
available data paths. Since satellite link 232d is unavailable, it
will not be considered. Thus, WiFi link 235d and WiMax link 234d
will be selected in a mirrored data configuration sending to
receive site 280d. Additionally, WiMax link 234d will be selected
to multicast data to corporate LAN 290. If WiMax link 234d did not
support multicasting, then the routing application could failsafe
to standard unicast transfer.
[0059] At step 410 of flowchart 400, data transmission unit 130
transmits the digital data using the selected plurality of data
paths from step 408. Unless the system is a degenerate case where
there is only a single digital repeater module or a direct path to
the receive site, the data transmission unit will have to rely on
the help of other digital repeater modules to relay the data. Thus,
step 410 may not travel all data paths in one step. Rather, step
410 will route the data to the most optimal neighbors, passing
along route identifiers or path structures to those neighbors,
enabling them in turn to correctly route the data along the chosen
paths.
[0060] Since one reason for adopting the present digital repeater
device is the additional reliability it provides for data transfer,
contingencies for unexpected issues, such as the failure of a
digital repeater device or a downed link for example, may be
desirable. In these cases, step 410 may fail midway because a route
that was once thought to be valid is now invalid because of missing
pathways. In this case, the digital repeater module can be
configured to return to step 404 to discover a new path that can
circumvent the problem leading to the failure of step 410. If the
network provides enough redundancy in the form of additional
digital repeater modules and communication links, there are likely
to be alternative paths available. Thus, much like the Internet,
the repeater network can provide a level of robustness correlated
to the number of routers (digital repeater modules) and data paths
available. However, if absolutely no paths are available, the
digital repeater module may have to wait and periodically check if
available paths have opened.
[0061] Turning to FIG. 5, FIG. 5 shows flowchart 500 describing the
steps, according to one embodiment of the present invention, by
which a digital repeater module may resolve assignment of limited
broadcast frequencies. Certain details and features have been left
out of flowchart 500 that are apparent to a person of ordinary
skill in the art. For example, a step may comprise one or more
substeps or may involve specialized equipment or materials, as
known in the art. While steps 502 through 508 indicated in
flowchart 500 are sufficient to describe one embodiment of the
present invention, other embodiments of the invention may utilize
steps different from those shown in flowchart 500.
[0062] Referring to step 502 in FIG. 5 and digital repeater system
300 of FIG. 3A, step 502 of flowchart 500 comprises digital
repeater module 310 receiving frequency and Global Positioning
System (GPS) data from a first broadcasting device, such as
broadcast device 350. In one embodiment, for example, broadcast
device 350 may have already retrieved a recent GPS data set from
GPS satellite 370 through satellite link 332a. As previously
mentioned, a real world implementation will use multiple GPS
satellites, but it is simplified to one satellite in FIG. 3A.
Broadcast device 350 will typically also have a frequency already
assigned to it, which in FIG. 3A is indicated as frequency A. These
data sets may then be transferred from broadcast device 350 to
digital repeater module 310 using link 371.
[0063] At step 504 of flowchart 500, the frequency and GPS data is
transmitted to frequency coordinator site 345. Since FIG. 3A has
only one digital repeater module with a direct link 373 to
frequency coordinator site 345, this step only involves
transmitting data through link 373. However, a more complicated
configuration such as digital repeater system 200 shown in FIG. 2
will involve steps similar to flowchart 400 illustrated in FIG. 4
and discussed above.
[0064] Steps 502 and 504 will be repeated on a periodic basis for
each broadcast device so that the positions of the broadcast
devices at the frequency coordinator site do not fall too out of
date. The shorter the time length between intervals, the more
up-to-date the frequency coordinator site will be. However, a short
interval also means more frequent data transfers, increasing the
processing overhead for the digital repeater devices. An interval
of a few minutes, for example, may effectively balance these
competing interests.
[0065] At step 506 of flowchart 500, digital repeater module 310
receives instructions from frequency coordinator site 345 to relay
to a second broadcasting device, broadcast device 351. In the
present example, these instructions comprise changing to frequency
B. This instruction can be generated through a multitude of
different methods as previously explained in conjunction with FIGS.
3A and 3B; the present system simply compares distance 325 to a
preset maximum threshold and triggers a warning to be acted upon by
a human decision maker. The decision maker decides to change
broadcast device 351 to frequency B. As previously discussed,
broadcast device 350 could also be told to change its frequency
instead, or either device could be told to shut off instead.
According to the present embodiment, frequency coordinator site 345
is responsible for setting up policies to decide the proper course
of action.
[0066] At step 508 of flowchart 500, digital repeater module 310
sends these instructions received from step 506 to the second
broadcasting device, such as broadcast device 351, using link 372,
thus resolving potential frequency conflicts. Once broadcast device
351 receives these instructions, it might immediately act upon them
or await authorization. As previously explained, broadcast device
351 might also forward the instructions to surrounding devices that
might rely on broadcast 351 for data uplink, such as, for example,
wireless portable cameras. Yet, broadcast device 351 might itself
represent a wireless portable camera. Once broadcast device 351
finishes executing the instructions it receives, the possibility of
frequency interference is averted due to a proper assignment of
limited broadcast frequencies, aided by the data relay capabilities
of digital repeater module 310.
[0067] As described in the foregoing, a digital repeater module and
method for relaying digital data supports a robust, flexible, error
tolerant data transfer network for ENG and other applications. No
longer are television studios tethered to their local receiver
tower or relay; with the easily deployable digital repeater module,
the operational radius of ENG teams can be extended on demand by
simply adding more modules and connections. Supporting multiple
concurrent reception and transmission links using advanced routing
methods, the digital repeater device provides reliability and
flexibility impossible with traditional single link methods.
Additionally, reliability of the network scales upwards by simply
adding redundant modules, allowing incremental upgrades to the
network as budget permits. When placed at a high vantage point, the
digital repeater module can also provide panoramic views of events
around it through a locally attached camera. These dramatic shots
are often highly sought in the ENG business, but require complex
and expensive equipment setup, wasting valuable time and resources.
With the digital repeater module, a high quality lightweight
portable camera can provide similar results in a fraction of the
usual deployment time. In addition, with the aid of GPS satellites,
the digital repeater module can help coordinate frequency
assignments for broadcast devices, further allowing ENG teams to
focus on their job rather than worry about technical issues. Not
only will ENG teams and television networks appreciate the benefits
of the digital repeater device, but the public will also feel
benefits from a wider, more reliable coverage of news and other
televised events.
[0068] From the above description of the invention it is manifest
that various techniques can be used for implementing the concepts
of the present invention without departing from its scope.
Moreover, while the invention has been described with specific
reference to certain embodiments, a person of ordinary skills in
the art would recognize that changes can be made in form and detail
without departing from the spirit and the scope of the invention.
As such, the described embodiments are to be considered in all
respects as illustrative and not restrictive. It should also be
understood that the invention is not limited to the particular
embodiments described herein, but is capable of many
rearrangements, modifications, and substitutions without departing
from the scope of the invention.
* * * * *